Can't user 5er again this winter - replace red goo in pipes?

As already pointed out multiple times, the antifreeze simply displaces any water in the pipes. Once the water's gone, it doesn't matter anymore. You don't need to add more antifreeze.

I use antifreeze to winterize, then drain it. That way that evil chemical taste/smell doesn't have time to penetrate into the lines. Though it's probably just fine, I can't bring myself to trust just blowing out the lines.